I have just re-read my post and perhaps should clarify...
My choices are:
Pull it apart and use the part; or
Try to find original blackstar rear pcb, power transformer plus an appropriate OT and rebuild as far as possible from OEM parts; or
Make my own rear end for the main HT-60 pcb, but not using OEM parts.
Of course, I could put it in a drawer and forget about it. I paid £30 for it, so I have a little headroom.
Finally, there are many threads on here about the challenges getting hold of Blackstar schematics. I have emailed Blackstar, but not heard back.
All the best